Server Notes

Random server oriented notes, all over the map
Device Mapper:
 lvdisplay|awk '/LV Name/{n=$3} /Block device/{d=$3;sub(".*:","dm-",d);print d,n;}'|sort -nk 3
 dmsetup ls|awk '{n=$1;d=$3;sub(")","",d); printf("dm-%s %s\n",d,n);}'|sort -nk 3


ISO Images with Linux
=====================
genisoimage -f -J -joliet-long -r -allow-lowercase -allow-multidot \
  -o foobar.iso path_to_directory_with_files


Notify / inotify
================
ps $(find /proc/*/fd/* -type l -lname 'anon_inode:inotify' 2>/dev/null \
  | sed 's+/proc/\([^/]*\)/fd/.*+\1+')
echo 1 > /sys/kernel/debug/tracing/events/syscalls/sys_exit_inotify_add_watch/enable
cat /sys/kernel/debug/tracing/tracing_on
grep -c inotify_add_watch /sys/kernel/debug/tracing/trace
echo 0 > /sys/kernel/debug/tracing/events/syscalls/sys_exit_inotify_add_watch/enable


VirtualBox
==========
$ vboxmanage showmediuminfo disk source.vhdx
$ vboxmanage clonemedium disk source.vhdx dest.vdi


LVM cluster volume work
=======================
https://access.redhat.com/solutions/3618
vgchange -cn --config 'global {locking_type=0}' vgsan00


Capture bash history of logged in user
======================================
PID=1234; gdb -batch --eval "set sysroot /" --eval "attach ${PID}" \
  --eval "call write_history(\"/tmp/history-${PID}.txt\")" \
  --eval 'detach' --eval 'q'


Add to glibc
============
MYGLIBC=$(rpm -q --queryformat='%{version}-%{release}\n' glibc | uniq)
yum --showduplicates --disableexcludes=all install nscd-${MYGLIBC}


RHEL Cluster check
==================
xmllint -relaxng /usr/share/cluster/cluster.rng /etc/cluster/cluster.conf


Tomcat SSL
==========
http://www.digicert.com/ssl-certificate-installation-tomcat.htm
- keyAlias="tomcat" keystoreFile="tomcat.jks" keypass="tomcat"

# openssl pkcs12 -export -name tomcat -in tomcat.crt -inkey tomcat.key -out tomcat.p12 -CAfile GeoTrust_Inc.cabundle -caname root
# keytool -importkeystore -destkeystore tomcat.jks -srckeystore tomcat.p12 -srcstoretype pkcs12 -alias tomcat
# keytool -list -v -keystore tomcat.jks


SSL cert checks
===============
openssl x509 -in XXX.crt -text | grep CN=
openssl x509 -modulus -noout -in XXXX.crt | openssl md5
openssl rsa -modulus -noout -in XXXX.key | openssl md5


Oracle nifties
==============
$ lsnrctl status <ID>
$ ps -ef|grep pmon |grep -vi grep|grep -vi asm (Oracle ASM)

$ ps -ef|grep crs (Oracle RAC)
$ su - oracle
$ sqlplus / as sysdba (it will show RAC is installed)
$ select * from gv$active_instances; (verify 100% if there is RAC)

http://docs.oracle.com/cd/B28359_01/server.111/b31107/asmdiskgrps.htm#CHDIBGGH


oracle database size check
-------------------------------
--- Acutal size of segments i.e. tables/indexes
select sum(bytes)/(1024*1024*1024) from dba_segments;
select sum(bytes)/(1024*1024*1024) from dba_data_files;
-- total size of data files

crosscheck
--------------------------------------
Login to “rman target backupadmin/pwd@tns catalog cname/passwd@catalog” once you get “RMAN>” prompt, please run the following:
RMAN> Crosscheck ARCHIVELOG ALL;

oracle query for list of the tablespaces
--------------------------------------
select tablespace_name, CONTENTS from dba_tablespaces;

oracle query for list of datafiles
--------------------------------------
SELECT NAME, FILE#, STATUS, CHECKPOINT_CHANGE# "CHECKPOINT" FROM V$DATAFILE;

https://docs.oracle.com/cd/B28359_01/server.111/b28310/dfiles010.htm#ADMIN11459
https://docs.oracle.com/cd/B19306_01/server.102/b14237/dynviews_1076.htm#REFRN30050

ASM disk timeouts

SQL> select name,value,describe from v$asm_hidden_paras;
NAME                                    VALUE    DESCRIBE
--------------------------------------- -------- ----------------------------------------------------------------------
_asm_acd_chunks                         1        initial ACD chunks created
[...]
_asm_global_dump_level                  267      System state dump level for ASM asserts
_asm_hbeatiowait                        15       number of secs to wait for PST Async Hbeat IO return
_asm_hbeatwaitquantum                   2        quantum used to compute time-to-wait for a PST Hbeat check


SCSI Device Ops
===============
echo "- - -" > /sys/class/scsi_host/hostX/scan where X is your HBA
echo 1 > /sys/block/sdX/device/rescan where X is your device number
echo 1 > /sys/block/sdX/device/delete where X is your device number


MySQL Things
============
MySQL slave check:
mysql -e "show slave status\G;" | awk '/Slave_IO_Running|Slave_SQL_Running|Seconds_Behind/'

MySQL killer for AmReg:
for x in `mysqladmin processlist | grep -i select | awk -F"|" ' $7 > 30 { print $2 }'` ; do mysqladmin kill $x ; done

MySQL real DB size by DB:
SELECT table_schema "Name", sum( data_length + index_length ) / 1024 / 1024 / 1024 "Size in GB" FROM information_schema.TABLES GROUP BY table_
schema;

MySQL real DB size by Engine:
select engine,count(*),sum(index_length+data_length)/1024/1024 from information_schema.tables group by engine;

MySQL table size of a single table:
SELECT  table_name,`engine`,ROUND(data_length/1024/1024,2) total_size_mb,ROUND(index_length/1024/1024,2) total_index_size_mb, table_rows FROM information_schema.TABLES WHERE table_schema = 'threadless' and table_name = 'users';

MySQL flush buffers for shutdown:
# mysql -e "flush logs;"
# mysql -e "SET @@global.innodb_max_dirty_pages_pct = 0;"
# mysql -e "show global status like ‘Innodb_buffer_pool_pages_dirty’;"
## mysqladmin ext -i10 | grep dirty

MySQL increase connections:
gdb -p $(cat /var/run/mysqld/mysqld.pid) -ex "set max_connections=5000" -batch

Some low disk things

Low Disk (current directory, w/top 20 on largest directories)
FS="$PWD";resize;clear;date;df -h $FS; echo "Largest Directories:"; nice -n19 find $FS -mount -type d -print0 2>/dev/null|xargs -0 du -k 2>/dev/null|sort -runk1|head -n20|awk -F'\t' '{printf "%8d MB\t%s\n",($1/1024),$NF}';echo "Largest Files:"; nice -n 19 find $FS -mount -type f -print0 2>/dev/null| xargs -0 du -k | sort -rnk1| head -n20 |awk -F'\t' '{printf "%8d MB\t%s\n",($1/1024),$NF}';

Low Disk (current directory, takes into account sparse files)
FS='./';resize;clear;date;df -h $FS; echo "Largest Directories:"; du -hcx --max-depth=2 $FS 2>/dev/null | grep [0-9]G | sort -grk 1 | head -15 ;echo "Largest Files:"; nice -n 19 find $FS -mount -type f -print0 2>/dev/null| xargs -0 du -k | sort -rnk1| head -n20 |awk -F'\t' '{printf "%8d MB\t%s\n",($1/1024),$NF}'
Index

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SPDX-License-Identifier: MIT